Magnetically levitated and driven blood pump and method for using the same
A device for pumping blood, includes a housing having a distal end adapted to be coupled to a catheter, a proximal end having an outlet, and a tubular body extending between the distal and proximal ends along an axis. A rotor is rotatably disposed within the housing. A first magnetic bearing is operative to levitate the rotor along the axis within the housing. A second magnetic bearing controls a rotational frequency of the rotor. A third magnetic bearing controls a radial position of the rotor.
1. A device for pumping blood, comprising:
a housing having a distal end adapted to be coupled to a catheter, a proximal end having an outlet, and a tubular body extending between said first distal and proximal ends along an axis;
a rotor rotatably disposed within the housing;
a first magnetic bearing operative to levitate the rotor along the axis within the housing;
a second magnetic bearing controlling a rotational frequency of the rotor;
a third magnetic bearing controlling a radial position of the rotor;
at least one Hall Effect sensor sensing the radial position and rotational frequency of the rotor; and
a controller operatively coupled to the sensor, wherein the controller is configured to selectively send a current to the second magnetic bearing to change or maintain the radial position and the rotational frequency of the rotor.
2. The device of claim 1 , wherein:
the first magnetic bearing comprises first and second permanent magnets; and
the second magnetic bearing comprises a plurality of electromagnetic coils and a pole structure coupled to the rotor; and
the third magnetic bearing comprises the plurality of electromagnetic coils and one of the first or second permanent magnets.
3. The device of claim 1 , wherein the first permanent magnet is embedded in the rotor.
4. The device of claim 3 , wherein the second permanent magnet is disposed distally relative to the first permanent magnet.
5. The device of claim 3 , wherein the second permanent magnet is a ring magnet concentrically disposed relative to the axis.
6. The device of claim 2 , wherein the pole structure comprises a first set of permanent sub-magnets circumferentially disposed about a center axis of the rotor.
7. The device of claim 6 , wherein the sub-magnets are embedded in the rotor.
8. The device of claim 6 , further comprising a second set of permanent sub-magnets circumferentially disposed around the center axis of the rotor, the second set more proximally located on the rotor.
9. The device of claim 6 , wherein the sub-magnets are cylindrically shaped and axially magnetized.
10. The device of claim 8 , wherein the permanent sub-magnets of the first and second sets are aligned, thereby essentially forming a plurality of vertically arranged pairs of sub-magnets.
11. The device of claim 8 , wherein the first and second sets each include at least four sub-magnets.
12. The device of claim 8 , wherein the first and second sets each include six sub-magnets.
13. The device of claim 9 , wherein an axis of magnetization of the sub-magnets is tangent to an axis of rotation of the rotor.
14. The device of claim 2 , wherein the plurality of electromagnetic coils further comprises four vertically arranged pairs of coils circumferentially disposed around the housing.
15. The device of claim 14 , wherein each pair of coils is counterwound.
16. The device of claim 1 , where the controller is a PID controller.
17. The device of claim 2 , wherein the plurality of electromagnetic coils further comprises a plurality of vertically arranged pairs of coils circumferentially disposed around the housing.
18. The device of claim 17 , wherein the controller sends a current to a pair of coils to change or maintain the rotational frequency of the rotor.
19. The device of claim 17 , wherein the controller sends a current to a pair of coils to change or maintain the radial position of the rotor.
20. The device of claim 17 , wherein:
the controller sends a current to diametrically opposed pairs of coils to change or maintain the rotational frequency of the rotor.
21. The device of claim 2 , wherein:
the controller sends a current to at least one pair of coils to change the radial position of the rotor.
22. The device of claim 2 , wherein the coils magnetically couple to the pole structure when a current is sent to the coils.
23. The device of claim 1 , further comprising a pin within the tubular body configured to support the rotor prior to an axial displacement thereof.
24. A device for pumping blood, comprising:
a housing having a distal end adapted to be coupled to a catheter, a proximal end having an outlet, and a tubular body extending between the distal and proximal ends along an axis;
a rotor rotatably disposed within the housing;
a first magnetic bearing further comprising first and second permanent magnets and operative to levitate the rotor to an axial position within the housing;
a second magnetic bearing further comprising a plurality of vertically arranged pairs of electromagnetic coils and a pole structure coupled to the rotor, the second magnetic bearing configured to change or maintain a rotational frequency of the rotor;
a third magnetic bearing further comprising the plurality of vertically arranged pairs of electromagnetic coils and the first permanent magnet, the third magnetic bearing configured to change or maintain a radial position of the rotor;
a Hall Effect sensor sensing the radial position and rotational frequency of the rotor; and
a controller operably coupled to the Hall effect sensor and configured to communicate with the coils to change or maintain the radial position and rotational frequency of the rotor.